Myelinogenesis will be examined using an hypothesis that murine mutants with disordered formation of myelin have a genetic error in the process of myelin membrane assembly. The experimental support for this hypothesis which has been obtained using the Quaking mutant will be further tested by the following: (1) examination of the Shiverer, Jimpy and MSD mutants using similar methods; (2) determination of the turnover of myelin proteins and lipids in these mutants, and; (3) exploration of membrane assembly in PNS myelin and perhaps in spermatids which are known to be affected in the Quaking mutant. We also propose a plausible model for the process of myelin assembly which may enable the study of the intracellular route of synthesis and transport of membrane constituents particularly proteins to the cell surface membrane. Eventually the mutants will be used in efforts to further delineate these intracellular sites and processes. The techniques used include isolation of membrane precursors of myelin, demonstration of myelin preproteins, systems for cell-free synthesis of myelin proteins and detailed analysis of protein primary structure.